a) $$x^{\frac{1}{3}} \cdot x^{\frac{2}{5}} = x^{\frac{1}{3} + \frac{2}{5}} = x^{\frac{5+6}{15}} = x^{\frac{11}{15}}$$ б) $$a^{\frac{1}{2}} \cdot a^{-\frac{1}{3}} = a^{\frac{1}{2} - \frac{1}{3}} = a^{\frac{3-2}{6}} = a^{\frac{1}{6}}$$ в) $$(x^5)^{\frac{1}{3}} = x^{5 \cdot \frac{1}{3}} = x^{\frac{5}{3}}$$ Ответ: a) $$x^{\frac{11}{15}}$$; б) $$a^{\frac{1}{6}}$$; в) $$x^{\frac{5}{3}}$$